/*
 * Copyright (C) 2012 Google Inc.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
 * use this file except in compliance with the License. You may obtain a copy of
 * the License at
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 */

package org.ros.concurrent;


/**
 * @author damonkohler@google.com (Damon Kohler)
 */
public class WallTimeRate implements Rate {

  private final long delay;

  private long time;

  public WallTimeRate(int hz) {
    delay = 1000 / hz;
    time = 0;
  }

  @Override
  public void sleep() {
    long delta = System.currentTimeMillis() - time;
    while (delta < delay) {
      try {
        Thread.sleep(delay - delta);
      } catch (InterruptedException e) {
        break;
      }
      delta = System.currentTimeMillis() - time;
    }
    time = System.currentTimeMillis();
  }
}
